Crews work to clean up oil at a beaver dam from a pipeline spill, owned by Plains Midstream Canada, 12kms from Little Buffalo 100kms from Peace River in northern Alberta on May 10, 2011. The 4.5 million litre spill is the largest in Alberta since 1975. (Jimmy Jeong/JimmyShoots.com)

Crews work to clean up oil at a beaver dam from a pipeline spill, owned by Plains Midstream Canada, 12kms from Little Buffalo 100kms from Peace River in northern Alberta on May 10, 2011. The 4.5 million litre spill is the largest in Alberta since 1975.(Jimmy Jeong/JimmyShoots.com)

For ages, about the only inhabitants of a secluded stretch of marshland outside this Lubicon Cree community were beavers and ducks. A kilometre deep in the bush from the nearest dirt road, the boggy area was visited by the occasional aboriginal trapper.

Now it's the site of what looks like a macabre sort of carnival. Brightly coloured plastic flags stretch across a 150-metre expanse to keep birds away. Heavy trucks lumber along makeshift roads. Hundreds of workers, many wearing coveralls, goggles and breathing through masks, toil in the marsh in a desperate effort to bring it back to life.

CTV video screen capture

Oil

A thick black coating covers the water and the walls of an old beaver dam, while the pungent smell of oil hangs in the air.

It's this marsh that caught nearly all of the estimated 28,000 barrels of light crude oil that spilled from Plains Midstream Canada's 45-year-old Rainbow pipeline on April 28. The oil ran 850 metres downhill and formed a pitch-black hockey stick-shaped pool in the northern muskeg.

The Rainbow spill is just the latest in a series of oil leaks in North America's vast pipeline network over the past year, and comes as Canadian energy giants are pressing to win approval for some of their most ambitious projects to date. Those include TransCanada Corp.'s Keystone XL pipeline to ship oil sands crude to the Gulf of Mexico, and Enbridge Inc.'s Northern Gateway pipeline to take Alberta crude to the British Columbia coast for shipment to then to Asia, a plan that faces fierce opposition from first nations.

The spills - some minor and some that have led to evacuations - raise questions about the safety of North America's pipeline network. Critics say many pipelines are old and prone to corrosion, and point to a regulatory system that may not be keeping pace with environmental risks and the need for quick response when things go wrong.

"Essentially, spills of this magnitude aren't supposed to happen," said Anthony Swift, a lawyer for the New York-based Natural Resources Defense Council, which is fighting the Keystone project. "If the pipeline operator was operating under current regulations, you'd perhaps have to ask, 'Are the regulations adequate?'"

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In Little Buffalo, residents say they were largely left in the dark by provincial officials for days after the spill, 12 kilometres from the community, while an acrid stench filled the air.

"We had to go to an American website to find out what actually was happening," said Carolyn Kolebaba, reeve of Northern Sunrise County, echoing the Lubicon's concerns about the slow response.

On the morning of April 29, a Friday, children at the Little Buffalo school began to complain of nausea, lack of appetite and headaches.

"We thought it was a propane leak," says teacher Mark Thorne, 25, one of a handful of teachers who live in trailers next to the school in the community of about 300. On winter days, it's not unusual for the school's propane system to clam up, causing problems. But this was spring.

The children were sent home. The school board sent out an inspector, who said there was no propane problem.

Steve Noskey and Bernard Ominayak, who both claim the title of Lubicon chief, were each called by Plains Midstream about midday Friday and told of an oil spill, though not how large. Mr. Noskey helped round up 10 local cleanup workers. He spoke with the principal of the school, but neither connected the dots, thinking a small spill and a possible propane problem were unconnected. Mr. Noskey admitted that was an oversight. "I would take responsibility for that," he said, but added that he wasn't told of the scale of the spill.

A weekend passed. On Monday the children arrived back at school, and again they complained of feeling sick. They were sent home.

"And as we were sending the kids out the door, one of the TAs [teaching assistants]was like, 'I think there's an oil spill actually. Oh, well, we haven't heard anything so I guess we'll have to wait and find out.' And that was on Monday," Mr. Thorne said.